1. Filed of the Invention
The present invention relates to a laminated chip electronic device and a method of manufacturing the same. More particularly, the present invention relates to a laminated chip electronic device with a non-linear resistance coefficient and a method of manufacturing the same, wherein an insulating layer is first formed on the top, bottom, front and back surfaces of a body of the laminated chip electronic device, so that subsequently formed electrodes are electroplated easily.
2. Description of the Related Art
Currently, laminated chip electronic devices (such as the one shown in FIG. 1) are widely used. Materials used for manufacturing the laminated chip electronic devices are various. Among these materials, non-linear resistance coefficient materials for manufacturing the bodies of the laminate chip electronic devices become more and more popular. The laminated chip electronic devices manufactured finally are to be used in electronic systems. For most laminated chip electronic devices, a soldering process is used to connect the two electrodes of each laminated chip electronic device to a circuit board of an electronic system, so that the laminated chip electronic device can normally operate in the electronic system. However, it still needs for the laminated chip electronic devices with their bodies made of a non-linear resistance coefficient material to have an easy-to-solder property. FIGS. 2A and 2B are schematic, cross-sectional views of a conventional laminated chip electronic device taken along a line A—A and a line B—B of FIG. 1, respectively. In FIGS. 2A and 2B, reference numerals 11, 12, 13 and 15 designate a body made of a non-linear resistance coefficient material, conductive layers, two electrodes and soldered interface layers, respectively.
However, the non-linear resistance coefficient material used to manufacture the body 11 of the conventional laminated chip electronic device of FIGS. 2A and 2B has a semiconductor property or does not have a high resistivity property. As a result, a process of forming the soldered interface layers 15 on the two electrodes 13, respectively, becomes very difficult.
To solve the above problem, there are three ways in the prior art as follows:                1. It is to adjust conditions of an electroplating process, and particularly to change the type and kind of an electroplating solution. When the body 11 of a laminated chip electronic device is electroplated, insulting parts of the device should not be adhered to by the soldered interface layers. In this way, an electroplating process can be used to form the soldered interface layers 15. However, particular production lines for the electroplating cannot be compatible with other products. This not only increases costs, but also needs different methods to treat particular electroplating wastewater, resulting in troubles to manufacture and increased costs. Moreover, an electroplating process can be performed for only parts of devices with a non-linear resistance coefficient material by setting specific conditions. For most devices with a non-linear resistance coefficient material, the soldered interface layers cannot be perfectly formed in an electroplating process, even though the conditions of the electroplating process are adjusted.        2. Referring to FIGS. 3A and 3B, after two electrodes 13 of a device are formed, two insulating layers 14 is formed on insulting parts of the device. As a result, when the soldered interface layers 15 are formed, they cannot be formed on the insulting layers 14. Since conventional laminated chip electronic devices are generally in a square shape, and the structure of the two electrodes 13 is first formed, the conventional laminated chip electronic devices are covered with the insulating layers 14 one by one, and each time only one surface of a conventional laminated chip electronic is covered with the insulating layer 14. As a result, this causes the manufacturing speed to slow down or yields to be reduced. For example, more equipment is needed to meet the requirements, causing high manufacturing costs.        3. Referring to FIGS. 4A and 4B, a conductive material used for two electrodes 13 contains special precious metal components (for example, platinum, palladium, etc.), so that the two electrodes can be used in a soldering process directly. However, the yields of the conventional laminated chip electronic devices are limited, and the prices of the devices are unstable, resulting from the limitations of the productions of the precious metals and the great variations of the prices of the precious metals. Moreover, the two electrodes are easy to oxidize, resulting in poor reliability. When used in a soldering process, the two electrodes can not have the same quality as those with soldered interface layers formed thereon.        